Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Certain medical states or conditions of a human body can be detected using sensors disposed outside of the human body (e.g., disposed against, on, or otherwise proximate an external body surface of the human body). Some medical states or conditions can change slowly, occur rarely, or otherwise indicate that monitoring of the human body over an extended period of time is preferred. A sensor disposed in a wearable device can enable long-term monitoring of a medical state or condition of the body of a wearer while allowing the wearer to perform activities of daily living, to travel, to commute, or to engage in other activities with minimal interruption. Such monitoring by a wearable device could be performed preventatively, e.g., to monitor an otherwise healthy wearer's health state over time to enable early detection of an adverse medical condition, to develop data describing a ‘healthy’ baseline state of the wearer, or to enable other applications. Medical states or conditions of a human body monitored by such a wearable device can include pulse rate, blood oxygenation, activity level, blood pressure, galvanic skin response, or other information about the body of a wearer.